Discussion
In this case, no optic nerve swelling or signal changes were evident on
imaging, but fundus examination revealed mild erythema of the optic
nerve papilla. Although this finding could be attributed to iritis, the
possibility of optic neuritis caused by an autoimmune mechanism in
IgG4-related disease could not be ruled out. However, the visual field
findings were not consistent with those commonly observed in optic
papillitis. Moreover, brain MRI findings suggested optic chiasm
compression due to pituitary enlargement. The patient’s visual acuity
and visual field defects improved following pituitary gland enlargement
after steroid treatment, suggesting that pituitary gland enlargement and
pituitary scrofula were the main pathophysiology of vision loss and
visual field defects.
The ophthalmologic clinical hallmark of IgG4-related ocular disease is
bilateral lacrimal gland enlargement with three features: suborbital
nerve enlargement, exophthalmos, and pressure optic
neuropathy2). IgG4-related optic neuropathy is
commonly caused by compression of the optic nerve by enlargement of the
lacrimal glands or other intraorbital
tissues2)5)6)7)8). Few studies have reported on optic
neuropathy caused by compression of the optic chiasm by an enlarged
pituitary gland as in the present case3)7)8). Although
bilateral hemianopsia is generally observed with pituitary enlargement,
the present case showed mild visual field defects in not only the
auriculolateral lower one-quarter blindness but also the nasal lower
one-quarter region. A previous study9) found visual
field defects in only one eye in two of 10 patients with symmetrical
pituitary enlargement. Because the present case also showed optic chiasm
compression due to pituitary enlargement, it is possible that it caused
an atypical visual field defect and associated visual acuity impairment.
Alternatively, as other studies have shown infiltration of IgG4-positive
plasma cells around the trigeminal nerve in the same
disease2), a deep infiltrative or inflammatory
mechanism may be involved in this case of optic neuropathy.
In conclusion, it is necessary to consider that the effects of
IgG4-related disease may be involved when patients complain of vision
loss and visual field impairment.
Declarations :
- State of Ethics: Ethical approval is not required for this study in
accordance with local or national guidelines. Written informed consent
was obtained from the patient for publication of the details of their
medical case and any accompanying images.
- Conflict of Interest: Not applicable.
- Funding Sources- No funding was obtained for this study.
- Author contributions and Data Availability: Shintaro Kohno, Hitoshi
Tabuchi and Atsuki Fukushima evaluated the findings of patients and
collected data. Shintaro Kohno and Atsuki Fukushima wrote the
manuscript. All data generated or analysed during this study are
included in this article.